Structure, spectroscopy, and theory calculations of mononuclear mixed-ligand copper(II) complex with malonate and 2-propylimidazole, [Cu(mal)(PIM)2(H2O)]

A mononuclear copper(II) complex, [Cu(mal)(PIM)2(H2O)] (1) [mal = malonate dianion, PIM = 2-propylimidazole] has been synthesized and characterized by elemental analysis, IR, UV–Vis, TG-DTA, and single crystal X-ray diffraction. The center Cu(II) atom in the complex has a distorted square-pyramidal geometry, being coordinated by two nitrogen atoms and three oxygen atoms. Density Functional Theory (DFT) with the B3LYP method and time-dependent DFT calculations were performed to provide insight into the structural, electronic, and electronic spectroscopic properties of the complex 1, and the UV–Vis spectrum of the title compound has been discussed on this basis. All the absorption bands in UV–Vis spectrum are mostly π/(P, σ) → dx2–y2 ligand-to-metal charge transfer (LMCT) transition, together with partial d → d ligand field (LF) transition.